Electrical Characteristics Analysis of LSCs Under Composite Fault

Large synchronous condensers (LSCs) are selected as the main dynamic reactive power compensation device for ultra-high voltage direct current (UHVDC) transmission systems. LSCs are subjected to sudden terminal voltage drops or rises for long periods of time during operations, which places high demands on their operational safety. This paper investigates steady-state and dynamic fault characteristics of LSCs under typical faults, i.e., rotor dynamic eccentricity, stator winding turn-to-turn short-circuit, and their composite fault. Stator winding circulating current and reactive power output are selected as the indicators to distinguish the faults. Fault characteristics are observed using a field-circuit coupled FEA model, and the test results performed on a real unit validates the conclusions.